The German, who headed into the final round with a slender one-stroke lead, held his nerve down the stretch to clinch his first victory of the season.

In the end it was comfortable enough for Kaymer as he enjoyed a two-shot cushion going down the last, but for a long time it looked hard to call the winner with five men all within a shot of the lead with nine holes remaining.

But Lee Westwood (73), Louis Oosthuizen (74) and Bill Haas (71) fell away on the back nine to finish fifth, fourth and third respectively as the tournament developed into a two-way battle.

Final leaderboard

Kaymer - who made a brilliant eagle at the second only to give it straight back with a double-bogey at the third - made a telling move around the turn as he birdied nine, ten and then 11 to move into the lead on his own at eight-under.

Crucial birdie

However, in the group ahead, Schwartzel kept the pressure on the German as he got up and down from the sand at the par-five 14th for a birdie that reduced the lead one to again.

Indeed, things looked to be wide open as Kaymer then pulled his drive at the same hole way left into undergrowth, seemingly leaving himself with no shot.

But he got a huge break as his ball found a decent lie in a little clearing, allowing him to chip back out on to the fairway and from there he would go on to make the most unlikely of birdies to regain control.

He did make a bogey at the next to offer Schwartzel renewed hope, but the South African's first and only bogey of the day after a poor chip at 17 all but decided things, allowing Kaymer to enjoy his walk up 18.

Untimely bogeys ensured Haas and Oosthuizen were never quite able to push on and mount a serious challenge, while Lee Westwood's bid for a third straight title was derailed by his frailties on the green as the Englishman again failed to take numerous chances.